Electrical timing circuit



y 1960 c. A. HACHEMEISTER 2,938,152

ELECTRICAL TIMING CIRCUIT Filed Dec. 16, 1957 E E: o 17/ I9 INVENTOR.Chaxl'eQAHnche/mebtdl ATTORNEY ELECTRICAL TIMING CIRCUIT Charles A.Hache'meistelghrooklyn, N.Y., assignor, by nesne assignments, to Leo C.Krazinski, New York,

2 Filed Dec. 16, 1957", set. No. 703,124 40min 01.317-142 Thisinvention'relates to an electrical control circuit, particularly to anelectrical timing circuit, and has for its primary object to provide atiming circuit having rapid recovery and substantially short timeintervals for fully' automatic filling machines of the type disclosed inUnited State Patent No. 2,660,336.

Another object of the invention is to provide a timing circuit forautomatic dispensers of liquid or viscous material.

Yet another object of the invention is to provide a timing circuit foruse in a dispenser adapted to inject 1 measured quantitiesof liquid ofviscous material into containers moving at a substantially high rate' ofspeed.

Still another object of the invention is to provide a timing circuit inwhich the time interval can be readily varied. I

(A further object of the invention is to provide a timing circuit whichis accurate in repetitive operation and which iscontrolled, by the powerline frequency.

A still further object of the invention is to provide a timing circuitin which the timing is initiated by the opening of a switch rather thanthe conventional closing of a switch.

Other and furtherobjects will be obvious upon an understanding of theillustrative embodiment about to be described, or will be indicated inthe appended claims, and various advantages not referred to herein willoccur to one skilled in the art upon employment of the invention inpractice.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description and is:. shown in. the accompanyingdrawings, forming a part of the specification, wherein the single figureshows a schematic view of an electrical timing circuit in accordane withthe invention.

Referring now, to the drawing, there is shown-a transformer having itsprimary winding 12 connected by leads 14 and 16 to a suitable" source ofpower, such as a conventioned 115 volt, 60 cycle alternating currentline. The transformer 10 has a secondary winding with a mid-tap 16, sothat the secondary winding is sub-divided into two winding portions 18and 20 with the voltages E and E respectively.

The outer end 19 of the secondary winding portion 18 is connected by alead 22 to a single pole, single throw switch 24, thence by a lead 26through an upper,

break contact 28 of a relay 30 and by a lead 32 to a juncture 33 of anadjustable resistor 34 in parallel with a capacitor 36. I The otherjuncture 37 of the resistor 34 and capacitor 36 isconnected by a lead 38to a grid of a vacuum tube 40. I

The outer end 19,0f the secondary winding portion 18 is also connectedby the lead 22 to a resistor 42 and a capacitor 44, in paralleL'and by alead 48 to a cathode of thevacuum tube 46.

The mid-tap 16 of the secondary winding of transformer 10 is connectedby a lead 50 to a cathode of the vacuum tube 40 and, by lead 52, to oneterminal of an adjustable resistor 54, the other terminal of resistor 54being connected to the outer end 19 of winding portion 18 via lead 56. Aresistor 58 is interposed between adjustable resistors 34 and 54, whichadjustable resistors are of the potentiometer type with sliding contacts57, 59 mechanically coupled together, as shown in dotted lines, tooperate as a unit. Resistor 58 is provided to prevent a short circuitacross the secondary winding por tion 18 when the sliding contact 59 isat the extreme right of resistor 54, as seen in the drawing, with switch24 closed. r

The outer end 60 of the other secondary winding portion 20 is connectedby lead 61 to a winding of the relay 30 and to a capacitor 62, both ofwhich are in parallel, the other sides of the relay winding andcapacitor 62 being connected by a lead 64 to the plate of the vacuum'tube 46. The grid of vacuum tube 46 is connected by a. lead 66 totheplate of vacuum tube 40, as well as to the other side of the parallelresistor 42 and capacitor 44.

The operation of the timing circuit will now be described. Assuming thatswitch 24 and relay contact 28 are in-their normally closed positions,as shown on the drawing, and assuming the power line is energized, thealternating current voltage E is applied, through lead 22, closed switch24, lead 26, closed relay contact 28,

lead 32, resistor 34 in parallel with capacitor 36, and lead 38, betweenthe grid and, .via lead 50, the cathode of vacuum tube'40. Duringpositive alternation of the voltage E 'the side of the capacitor 36 atthe juncture 33 becomes positive while the other-side of the capacitorat the juncture 37 becomes negative, thereby withdrawing from the gridof vacuum tube 40 some of the grids electrons. rent on positive peaks ofthe voltage E to develop an average voltage V across the parallelresistor 34 and capacitor 36, polarized negative at juncture 37, asindicated. The value of this voltage V is approximately equal to thecrest value of the voltage E The voltage E is also applied, through lead22 and resistor 42 in parallel with the capacitor 44, between the plateand, via lead 50, the cathode of vacuum tube 40. The plate conductscurrent on the positive peaks of the E voltage because the grid voltageis essentially in phase with the impressed plate voltage and there isdeveloped an average voltage V across the parallel resistor 42 andcapacitor 44.

The entire secondary voltage, that is, E plus E is applied through lead61, winding of relay 30 in parallel with the capacitor 62, and lead 64,between the plate and, via leads 22 and 48, the cathode of vacuum tube46. Since the voltage V developed because of the rectifica- Patented May24, 1960 Thus the grid becomes positive and conducts curtion by tube 40,produces a large negative bias on the grid of tube 46 (via lead 66),tube 46 does not conduct current even when its plate voltage is positiverelative to its cathode.

The timing circuit is now ready and, to start its timing interval, theswitch 24 is opened, either manually or automatically by a container asit moves by. The gridto-cathode voltage of vacuum tube 40 then becomes E-V where voltage E is sinusoidal and voltage V becomes a decayingexponential voltage. Voltage E is made sutliciently smaller than voltageE by means of the voltage divider (resistor) 54, so that the vacuum tube40 is rendered ineffective.

The voltage V across resistor 42 and capacitor 44 then decreases to thepoint where the grid-to-cathode bias on the vacuum tube 46 becomessufiiciently small to allow tube 46 to conduct current and therebydevelop an average voltage V across the winding of relay 30. Relay 30energizes in a circuit that can be traced from the outer terminal 60 ofthe secondary winding of transformer 10 via Iead, 61, winding of relay30, lead 64, plate and cathode of vacuum tube 46, lead 48 and thenceover lead 22 to the outer terminal 19 of the secondary winding. Relay30, in operating, opens the normally closed contact 28 and also anyother contacts associated with this relay, such as a solenoid by-passbreak contact 68, and closes a make-contact 70 for energizing a circuit,such as a discharge valve solenoid circuit. 24 may now be closed withoutdisturbing the subsequent operation of the timing circuit.

The voltage V continues to decay until it causes the grid-to-eathodevoltage on vacuum tube 40 to become less negative. When the cut-off gridvoltage corresponding to the transformer voltage E is reached, vacuumtube 40 becomes conductive, voltage V is increased and vacuum tube 46 isrendered ineifective. Relay 30 accordingly releases to restore contacts28, 68 and 70 to their initial conditions. Thereupon, with switch 24 andrelay contact 28 closed the timing circuit is restored to its initialcondition for another timing interval by the reopening of switch 24.

It is ot be particularly noted that the circuit for, the timingcapacitor 36 and resistor 34 includes no external resistance, as inconventional practice. The capacitor 36 and parallel resistor 34 areconnected directly acrossthe grid of vacuum tube 40 and the transformerwinding portion 18 under control of the serially connectedtrigger switch24 and relay contact 28. Consequently, the low resistance of thegrid-cathode conduction circuit of the vacuum tube 4!) enables thecapacitor 36 to be charged much faster then heretofore had beenpossible. Also, this low resistance factor permits triggering orstarting of the time interval by switch 24 at short, aperiodicItirneintervals without appreciably alfecting the time interval subsequent tosaid triggering.

For shorter periods, the time interval is primarily controlled by thefrequency of the power source and is equal to an integral number ofperiods of the power line voltage plus a part-period which is controlledby adjusting the amplitude of the alternating current grid-bias voltageE of vacuum tube 40 and, to a minor degree, the timeconstant ofcapacitor 36 and resistor 34.

Should the power line voltage change (within the normal limits), theratios of all the voltages which are pertinent to accurate timing remainsubstantially constant. Because the timing is affected only by theratios of voltages, usual power line fluctuations therefore have verylittle affect on the time interval.

From the foregoing description, it will be seen that the presentinvention provides a practical, reliable and fast operating timingcircuit particularly for automatic dispensers of liquid or viscousmaterial.

As various changes may be made in the form, construction, andarrangement of the parts herein, without departing from the spirit andscope ofthe invention and without sacrificing any of its advantages, itis to be understood that all matters are to be interpreted asillustrative and not in any limiting sense.

What is claimed is:

1. An electronic timing device comprising, in combination, atransformer, a primary winding in said transformer adapted forconnection to an alternating current supply source, a secondary windingin said transformer with a mid-tap, a first electronic tube with ananode, cathode and grid, said mid-tap of said secondary winding beingconnected to said cathode, a capacitor in parallel with a resistorinterconnected between one terminal of said secondary Winding and saidanode, a second capacitor in parallel with a second resistorinterconnected between said one terminal of said secondary winding andsaid grid, a third resistor bridged across said rnid-tap -andgrid,a.relay interposed between theotherterminalf said secondary winding andthe second anode, said second The switch cathode being connected to saidone terminal of said secondary winding, said first anode being connectedto said second grid, a normally closed switch, and a normally closedcontact of said relay, said switch and said closed contact beingserially interposed between said one terminal of said secondary windingand said second resistor.

2. An electronic timing device in accordance with claim 1, wherein saidsecond and third resistors are adjustable.

3. An electronic timing device comprising, in combination, atransformer, a primary winding in said transformer adapted forconnection to an alternating current supply source, a secondary windingin said transformer with a mid-tap, a first electronic tube with ananode, cathode and grid, said mid-tap of said secondary winding beingconnected to said cathode, a capacitor in parallel with a resistorinterconnected between one terminal of said secondary winding and saidanode, a second capacitor in parallel with an adjustable resistorinterconnected between said one terminal of said secondary wind ing andsaid grid, a voltage divider bridged across said mid-tap and said oneterminal of said secondary winding, and connected to said adjustableresistor, a sliding contact for said adjustable resistor and voltagedivider mechanically coupled for unitary movement, the sliding contactfor said adjustable resistor being connected to a terminal of saidadjustable resistor opposite said grid, a second electronic tube With ananode, cathode and grid,

a relay interposed between the other terminal of saidsecondary windingand the second anode, said second cathode being connected to said oneterminal of said secondary winding, said first anode being connected tosaid second grid, a normally closed switch, and a normally closedcontact of said relay, said switch and said closed contact beingserially interposed between said one terminal of said secondary windingand said adjustable resistor.

4. An electronic timingdevice comprising, in combination, a transformer,a primary winding in said transformer adapted for connection to analternating current supply source, a secondary winding in saidtransformer with a mid-tap, a first electronic tube with an anode,cathode and grid, said mid-tap of said secondary winding being connectedto said cathode, a capacitor in parallel with a resistor interconnectedbetween one terminal of said secondary winding and said anode, a secondcapacitor in parallel with an adjustable resistor interconnected betweensaid one terminal of said secondary winding and said grid, a secondadjustable resistor bridged across said mid-tap and said one terminal ofsaid secondary winding, a sliding contact for said adjustable resistorsmechanically coupled for unitary movement, the sliding contactassociated with said first adjustable resistor being connected to aterminal of said first adjustable resistor opposite said grid, a fourthresistor interconnected between said sliding contacts, a secondelectronic tube with an anode, cathode and grid, a relay interposedbetween the other terminal of said secondary winding and the secondanode, said second cathode being connected to said one terminal of saidsecondary winding, said first anode being connected'to said second grid,a normally closed switch, and a normally closed contact of said relay,said switch and said closed contact being serially interposed betweensaid one terminal of said secondary winding and said first adjustableresistor, said switch being opened to initiate a timing interval of saiddevice.

References Cited in the file of this patent UNITED STATES PATENTS2,454,168 Hartwig Nov. 16, 1948 2,516,422 Rockafellow July 25, 19502,790,115 Elliot Apr. 23, 1957 2,890,750 Depken June 16, 1959 FOREIGNPATENTS 136,892 Australia Apr. 4, 1950

